Method and apparatus for providing call routing in a network

ABSTRACT

A method and an apparatus for providing call routing in a network are disclosed. For example, the method receives a signaling message for a call, and determines if the signaling message contains information for determining if routing of the call requires an ENUM (tElephone Numbering Mapping) query. The method then processes the call by bypassing the ENUM query if the signaling message contains the information.

The present invention relates generally to communication networks and,more particularly, to a method and apparatus for providing efficientcall routing in a network, e.g., an Internet Protocol (IP) network, aVoice over Internet Protocol (VoIP) network, and the like.

BACKGROUND OF THE INVENTION

When a customer initiates a call, the call is routed to the networkservice provider for handling, where the call is processed and forwardedtowards its destination. Generally, in processing the call, a number ofprocessing steps is performed such as determining the call's termination(e.g., IP termination versus Public Switched Telephone Network (PSTN)termination). Many of these processing steps are performed irrespectiveof the type of calls that are being handled by the network serviceprovider. However, performing these processing steps may not be usefulfor a particular call.

SUMMARY OF THE INVENTION

In one embodiment, the present invention discloses a method and anapparatus for providing call routing in a network. For example, themethod receives a signaling message for a call, and determines if thesignaling message contains information for determining if routing of thecall requires an ENUM (tElephone Numbering Mapping) query. The methodthen processes the call by bypassing the ENUM query if the signalingmessage contains the information.

BRIEF DESCRIPTION OF THE DRAWINGS

The teaching of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates an exemplary network related to the presentinvention;

FIG. 2 illustrates an exemplary network in accordance with oneembodiment of the current invention for providing efficient callrouting;

FIG. 3 illustrates a flowchart of a method for providing call routing ina network; and

FIG. 4 illustrates a high-level block diagram of a general-purposecomputer suitable for use in performing the functions described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures.

DETAILED DESCRIPTION

The present invention broadly discloses a method and apparatus forproviding efficient call routing in a network. Although the presentinvention is discussed below in the context of Internet Protocol (IP)Multimedia Subsystem (IMS) networks, the present invention is not solimited. Namely, the present invention can be applied to packet networksin general, e.g., Internet Protocol (IP) networks, Voice over InternetProtocol (VoIP) networks, Service over Internet Protocol (SoIP)networks, and the like.

To better understand the present invention, FIG. 1 illustrates anexample network 100, e.g., an Internet Protocol (IP) MultimediaSubsystem network related to the present invention. An IP network isbroadly defined as a network that uses Internet Protocol to exchangedata packets. Exemplary IP Multimedia Subsystem (IMS) networks includeInternet protocol (IP) networks such as Voice over Internet Protocol(VoIP) networks, Service over Internet Protocol (SoIP) networks, and thelike.

In one embodiment, the network 100 may comprise a plurality of endpointdevices 102-104 configured for communication with the core IMS network110 (e.g., an IP based core backbone network supported by a serviceprovider) via an access network 101. Similarly, a plurality of endpointdevices 105-107 are configured for communication with the IMS corepacket network 110 via an access network 108. The network elements 109and 111 may serve as gateway servers or edge routers for the network110.

The endpoint devices 102-107 may comprise customer endpoint devices suchas personal computers, laptop computers, Personal Digital Assistants(PDAs), and the like. The access networks 101 and 108 serve as a meansto establish a connection between the endpoint devices 102-107 and theNetwork Elements (NEs) 109 and 111 of the IMS core network 110. Theaccess networks 101 and 108 may each comprise a Digital Subscriber Line(DSL) network, a broadband cable access network, a Local Area Network(LAN), a Wireless Access Network (WAN), a 3^(rd) party network, and thelike. The access networks 101 and 108 may be either directly connectedto NEs 109 and 111 of the IMS core network 110, or indirectly throughanother network.

Some NEs (e.g., NEs 109 and 111) reside at the edge of the IMS coreinfrastructure and interface with customer endpoints over various typesof access networks. An NE that resides at the edge of a coreinfrastructure is typically implemented as an edge router, a mediagateway, a proxy, a border element, a firewall, a switch, and the like.An NE may also reside within the network (e.g., NEs 118-120) and may beused as a SIP server, a core router, or like device.

The IMS core network 110 also comprises a Home Subscriber Server (HSS)127, a Serving-Call Session Control Function (S-CSCF) 121, a MediaServer (MS) 125, and an Application Server 112 that contains a database115. An HSS 127 refers to a network element residing in the controlplane of the IMS network that acts as a central repository of allcustomer specific authorizations, service profiles, preferences, etc.

The S-CSCF 121 resides within the IMS core infrastructure and isconnected to various network elements (e.g., NEs 109 and 111) using theSession Initiation Protocol (SIP) over the underlying IMS based corebackbone network 110. The S-CSCF 121 may be implemented to registerusers and to provide various services (e.g., VoIP services). The S-CSCFinteracts with the appropriate VoIP/SoIP service related applicationsservers (e.g., 112) when necessary. The S-CSCF 121 performs routing andmaintains session timers. The S-CSCF may also interrogate an HSS toretrieve authorization, service information, user profiles, etc. Inorder to complete a call that requires certain service specificfeatures, the S-CSCF may need to interact with various applicationservers (e.g., various VoIP servers). For example, the S-CSCF may needto interact with another server for translation of an E.164 voicenetwork address into an IP address, and so on.

The Media Server (MS) 125 is a special server that typically handles andterminates media streams to provide services such as announcements,bridges, and Interactive Voice Response (IVR) messages for VoIP serviceapplications. The media server also interacts with customers for mediasession management to accomplish tasks such as process requests.

The application server 112 may comprise any server or computer that iswell known in the art, and the database 115 may be any type ofelectronic collection of data that is also well known in the art. Thoseskilled in the art will realize that the communication system 100 may beexpanded by including additional endpoint devices, access networks,network elements, application servers, etc. without altering the scopeof the present invention.

The above IP network is described to provide an illustrative environmentin which packets for voice and data services are transmitted on IPMultimedia Subsystem (IMS) networks. When a customer initiates a call,the signaling message for the call is routed towards the serviceprovider's network. An S-CSCF located in the provider's networkprocesses the signaling message, and forwards the call towards itsdestination. In processing the call, a number of processing steps isperformed such as determining the call's termination (e.g., IPtermination versus Public Switched Telephone Network (PSTN)termination). Many of these processing steps are performed irrespectiveof the type of calls that are being handled by the network serviceprovider. However, performing these processing steps may not be usefulfor a particular call.

For example, an S-CSCF may process all calls the same way whether thecall is destined to an IP network or Public Switched Telephone Network(PSTN). In one example, the S-CSCF queries an ENUM server regardless ofthe network to which the call is destined.

In one embodiment, the current method provides efficient call routing ina network. Specifically, the current method provides a call routingmethod that includes bypassing the ENUM server if it is determined thatan ENUM query is not needed to handle the call. In order to more clearlydescribe the current invention, the following networking terminologiesare first provided.

-   -   E.164; and    -   ENUM (tElephone NUmbering Mapping).

E.164 refers to an ITU (International Telecommunications Union)-Trecommendation which defines the international public telecommunicationnumbering plan for formatting telephone numbers such that they may besignaled across one or more networks. The E.164 format includes acountry code and subsequent digits, but not the international prefix.

ENUM (tElephone NUmbering Mapping) refers to a standard protocol definedby the Internet Engineering Task Force (IETF) for translating phonenumbers that are in E.164 format to Internet domain names such that aDomain Name Server (DNS) may resolve the IP addresses for E.164 numbersthe same way it resolves traditional website domains. For example, ENUMmay be used to transform a phone, a fax or a pager number into a URI(Uniform Resource Identifier).

In order to translate a phone number to an Internet domain name, thephone number is first provided in an E.164 format. Specifically, thephone number is first translated or converted to a full E.164 formattednumber. For example, the original phone number may not have indicated acountry code, area code, etc. However, an E.164 formatted phone numberincludes a country code, area code and the specific number within thearea code. For example, “1” is the country code for all phone numbers inthe United States of America (USA). If the original USA phone number is987-555-1234, it is translated to an E.164 formatted number yielding1-987-555-1234. The E.164 number is then reduced to digits only, e.g.,19875551234. The digits are then reordered back to front, e.g.43215557891. Once the digits are reordered, dots are placed between eachdigit and the Internet domain e164.arpa is added to the end. For theabove example, the resulting Internet domain is4.3.2.1.5.5.5.7.8.9.1.e164.arpa. An S-CSCF server may then query a DNSserver to resolve on the domain name 4.3.2.1.5.5.5.7.8.9.1.e164.arpa.

As the example above illustrates, the ENUM query is useful when a callis routed to an IP endpoint by first transforming a phone number to aURI. However, if the call is destined to an endpoint in a PublicSwitched Telephone Network (PSTN), transforming a phone number to a URImay not be needed.

In one embodiment, the current method provides an efficient callrouting, e.g., by bypassing ENUM query processing or handling. Forexample, the method first determines if a signaling message for a callcontains a prefix that is used for determining whether or not the callrouting requires an ENUM query.

In one embodiment, the S-CSCF may receive a signaling message thatcontains a Carrier Identification Code (CIC). If the signaling messagecontains a CIC, the S-CSCF will use the CIC to identify the carriernetwork to which the signaling message is to be forwarded (e.g., usingthe following illustrative format: sip:+12127654321;cic=+10288@domain;user=phone). That is, the S-CSCF will be able to handle the callwithout performing an ENUM query.

The signaling message may then be forwarded to the identified carriernetwork via a Border Gateway Control Function (BGCF). For example, ifthe call is intended for PSTN termination, the BGCF may forward thesignaling message towards the PSTN network via a Media Gateway ControlFunction (MGCF). The MGCF may then convert the IP signaling message(e.g., Session Initiation Protocol message) to a signaling message for aswitched network (e.g., Signaling System 7), and then forward thesignaling system 7 message to a Signaling Gateway (SGW). The SGW maythen provide the signaling interface to the PSTN. Note that searchingfor a URI would not have been a useful step since the call is destinedto a circuit switched network, i.e., PSTN. Hence, bypassing the ENUMquery for such calls enables the S-CSCF to be more efficient in routingcalls. In other words, the interaction between the S-CSCF and an ENUMserver is avoided, thereby increasing the speed of setting up the calland avoiding using network resources unnecessarily.

In one embodiment, the S-CSCF may receive a signaling message thatincludes an indication, wherein the indication indicates that an ENUMquery if executed would result in the destination number beingidentified as a number that is not in service. For example, the callermay be aware that the called number is not available and the call may beintended to be handled in accordance with the called party's preferencewhen the called party is unavailable. For example, the caller may knowthat the called party is unavailable and the call needs to be forwardedto an answering service. In another example, the caller may know thatthe called party has invoked a call forwarding feature, e.g., to a cellphone. The caller may then include a predetermined prefix (e.g.,published by a service provider) in the signaling message such that theS-CSCF may use the predetermined prefix to identify the call as beingdirected towards a destination known to be unavailable. The S-CSCF maythen process the call without an ENUM query. That is, the predeterminedprefix may be used to make the S-CSCF aware that an ENUM query would notresult in obtaining a URI. For example, the S-CSCF may forward the calldirectly to an answering service, a cellular network for a cell phone,etc. without the need for performing an ENUM query.

FIG. 2 illustrates an exemplary network 200 in accordance with oneembodiment of the current invention for providing efficient callrouting. In one embodiment, the network 200 comprises a User Endpoint(UE) device 102 communicating with an IMS network 110 via an accessnetwork 101. The IMS network 110 comprises an HSS 127, an S-CSCF 121, anENUM server 228, and a BGCF 227.

In one embodiment, the current method provides an efficient call routingin a network. For example, the method enables a customer to subscribe toa service with a capability for bypassing an ENUM query. For example,the customer may access a Home Subscriber Server (HSS) 127 located inthe IMS network 110 and subscribes to the service. The HSS may thenprovide a predetermined prefix to the customer such that the customer isable to initiate calls with the signaling message containing thepredetermined prefix.

The service provider then implements within an S-CSCF 121 a method forprocessing a signaling message by first identifying whether or not thecall requires an ENUM query. For example, the method may first determineif the signaling message contains information (e.g., a CIC or apredetermined prefix for bypassing ENUM) that may be used to assesswhether or not the routing of the call requires an ENUM query. If thecall requires an ENUM query, the method queries the ENUM server 228 anduses a normal process for processing calls. The response to the ENUMquery may comprise one of: a SIP-URI, an indication that the request isto be forwarded to the PSTN, an indication that the E.164 number is notin the queried ENUM domain, and an indication that the E.164 number isnot in service. In one example, the ENUM query results in receiving aURI. The method may then replace the call signaling message (e.g., a SIPrequest) with a SIP-URI and routes the call towards the IP endpoint. Inanother example, the ENUM query may result in a response that indicatesthat the E.164 number is not in the queried ENUM domain. For example, a“no record found” response may be received from the ENUM server. Themethod may then route the request to the BGCF.

If the call requires no ENUM query, the method may then bypass ENUM. Inone embodiment, the signaling message may contain a particular CICidentifying a specific carrier. The call may then be forwarded to theappropriate carrier via a BGCF 227. In another embodiment, the signalingmessage may contain the predetermined prefix indicating that an ENUMquery would not result in a response that yields a URI. The method maythen handle the call in accordance with the call handling procedures forthe destination number. For example, the HSS 127 may include the callednumber's preference in handling incoming calls while the called numberis unavailable, e.g., the called party is busy, the called party haspowered off the phone, the called party has activated a “do not disturb”feature, and so on. The S-CSCF 121 may then consult with HSS 127 todetermine the proper call handling process.

FIG. 3 illustrates a flowchart of a method 300 for providing callrouting in a network. The current method provides efficient call routingby identifying calls that may bypass ENUM processing, i.e., processingsuch calls without issuing an ENUM query. For example, one or more stepsof method 300 can be implemented in an S-CSCF. Method 300 starts in step305 and proceeds to step 310.

In step 310, method 300 receives a signaling message for a call. Forexample, a Serving-Call Session Control Function (S-CSCF) receives aSession Initiation Protocol (SIP) signaling message for initiating acall.

In step 320, method 300 determines if the signaling message containsinformation indicating or for determining if the routing of the callrequires an ENUM query. In one embodiment, the information fordetermining if the routing of the call requires an ENUM query may be aCarrier Identification Code (CIC). In another embodiment, theinformation for determining if the routing requires an ENUM query may bea predetermined prefix for bypassing ENUM query. If the signalingmessage contains information for determining if the routing requires anENUM query (e.g., a predetermined prefix for bypassing ENUM and/or aCIC), the method proceeds to step 330. Otherwise, the method proceeds tostep 340.

In step 330, method 300 bypasses ENUM processing. For example, themethod skips the process of issuing an ENUM query for retrieving the URIof the destination endpoint for the call. The method then proceeds tostep 350.

In step 340, method 300 queries an ENUM domain server. For example, themethod may send a query to the ENUM domain server to retrieve a URIassociated with an IP endpoint. For example, the call may be destined toan endpoint in the IP domain. The method then proceeds to step 350.

In step 350, method 300 processes the call in accordance with a normalprocedure. For example, if the call is processed without an ENUM query,the method forwards the signaling message to a BGCF. In another example,if a URI is returned as a response to the ENUM query, the methodreplaces the URI with a SIP-URI (if SIP signaling is used) and routesthe signaling message towards the IP endpoint. The method then ends instep 360 or returns to step 310 to continue receiving additionalrequests.

It should be noted that although not specifically specified, one or moresteps of method 300 may include a storing, displaying and/or outputtingstep as required for a particular application. In other words, any data,records, fields, and/or intermediate results discussed in the method canbe stored, displayed and/or outputted to another device as required fora particular application. Furthermore, steps or blocks in FIG. 3 thatrecite a determining operation or involve a decision, do not necessarilyrequire that both branches of the determining operation be practiced. Inother words, one of the branches of the determining operation can bedeemed as an optional step.

FIG. 4 depicts a high-level block diagram of a general-purpose computersuitable for use in performing the functions described herein. Asdepicted in FIG. 4, the system 400 comprises a processor element 402(e.g., a CPU), a memory 404, e.g., random access memory (RAM) and/orread only memory (ROM), a module 405 for providing call routing in anetwork, and various input/output devices 406 (e.g., storage devices,including but not limited to, a tape drive, a floppy drive, a hard diskdrive or a compact disk drive, a receiver, a transmitter, a speaker, adisplay, a speech synthesizer, an output port, and a user input device(such as a keyboard, a keypad, a mouse, and the like)).

It should be noted that the present invention can be implemented insoftware and/or in a combination of software and hardware, e.g., usingapplication specific integrated circuits (ASIC), a general purposecomputer or any other hardware equivalents. In one embodiment, thepresent module or process 405 for providing call routing in a networkcan be loaded into memory 404 and executed by processor 402 to implementthe functions as discussed above. As such, the present method 405 forproviding call routing in a network (including associated datastructures) of the present invention can be stored on a computerreadable medium, e.g., RAM memory, magnetic or optical drive or disketteand the like.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

What is claimed is:
 1. A method for providing call routing in a network,comprising: receiving, by a processor of a serving-call session controlfunction, a signaling message for a call; determining, by the processor,if the signaling message contains information for determining if routingof the call requires a telephone numbering mapping query, wherein theinformation comprises a carrier identification code, wherein the carrieridentification code identifies a carrier to which the signaling messageis to be forwarded, wherein the network comprises an internet protocolnetwork; and processing, by the processor, the call by bypassing thetelephone numbering mapping query if the signaling message contains theinformation.
 2. The method of claim 1, wherein the information furthercomprises a predetermined prefix for bypassing a telephone numberingmapping processing.
 3. The method of claim 2, wherein the predeterminedprefix is determined by a service provider.
 4. The method of claim 1,wherein the signaling message comprises a session initiation protocolsignaling message.
 5. The method of claim 1, wherein the internetprotocol network comprises an internet protocol multimedia subsystemnetwork.
 6. The method of claim 5, wherein the internet protocolmultimedia subsystem network comprises a voice over internet protocolnetwork.
 7. A non-transitory computer-readable medium storing aplurality of instructions which, when executed by a processor of aserving-call session control function, cause the processor to performoperations for providing call routing in a network, the operationscomprising: receiving a signaling message for a call; determining if thesignaling message contains information for determining if routing of thecall requires a telephone numbering mapping query, wherein theinformation comprises a carrier identification code, wherein the carrieridentification code identifies a carrier to which the signaling messageis to be forwarded, wherein the network comprises an internet protocolnetwork; and processing the call by bypassing the telephone numberingmapping query if the signaling message contains the information.
 8. Thenon-transitory computer-readable medium of claim 7, wherein theinformation further comprises a predetermined prefix for bypassing atelephone numbering mapping processing.
 9. The non-transitorycomputer-readable medium of claim 8, wherein the predetermined prefix isdetermined by a service provider.
 10. The non-transitorycomputer-readable medium of claim 7, wherein the signaling messagecomprises a session initiation protocol signaling message.
 11. Thenon-transitory computer-readable medium of claim 7, wherein the Internetprotocol network comprises an internet protocol multimedia subsystemnetwork.
 12. The non-transitory computer-readable medium of claim 11,wherein the internet protocol multimedia subsystem network comprises avoice over internet protocol network.
 13. An apparatus for providingcall routing in a network comprising: a processor of a serving-callsession control function; and a computer-readable medium storing aplurality of instructions which, when executed by the processor, causethe processor to perform operations, the operations comprising:receiving a signaling message for a call; determining if the signalingmessage contains information for determining if routing of the callrequires a telephone numbering mapping query, wherein the informationcomprises a carrier identification code, wherein the carrieridentification code identifies a carrier to which the signaling messageis to be forwarded, wherein the network comprises an internet protocolnetwork; and processing the call by bypassing the telephone numberingmapping query if the signaling message contains the information.
 14. Theapparatus of claim 13, wherein the information further comprises apredetermined prefix for bypassing a telephone numbering mappingprocessing.
 15. The apparatus of claim 14, wherein the predeterminedprefix is determined by a service provider.
 16. The apparatus of claim13, wherein the signaling message comprises a session initiationprotocol signaling message.
 17. The apparatus of claim 13, wherein theinternet protocol network comprises an internet protocol multimediasubsystem network.